<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width,minimum-scale=1.0,maximum-scale=1.0,user-scalable=no">
    <title>Title</title>
    <script src="js/jquery.min.js"></script>
    <style>
        * {
            margin: 0;
            padding: 0;
            -webkit-box-sizing: border-box;
            -moz-box-sizing: border-box;
            box-sizing: border-box;
        }
        body {
            background: #2d2c41;
        }
        ul {
            list-style-type: none;
        }

        a {
            color: #b63b4d;
            text-decoration: none;
        }

        /** =======================
         * Contenedor Principal
         ===========================*/
        h1 {
            color: #FFF;
            font-size: 24px;
            font-weight: 400;
            text-align: center;
            margin-top: 80px;
        }

        h1 a {
            color: #c12c42;
            font-size: 16px;
        }

        .accordion {
            width: 100%;
            max-width: 360px;
            margin: 30px auto 20px;
            background: #FFF;
            -webkit-border-radius: 4px;
            -moz-border-radius: 4px;
            border-radius: 4px;
        }

        .accordion .link {
            cursor: pointer;
            display: block;
            padding: 15px 15px 15px 42px;
            color: #4D4D4D;
            font-size: 14px;
            font-weight: 700;
            border-bottom: 1px solid #CCC;
            position: relative;
            -webkit-transition: all 0.4s ease;
            -o-transition: all 0.4s ease;
            transition: all 0.4s ease;
        }

        .accordion li:last-child .link {
            border-bottom: 0;
        }

        .accordion li i {
            position: absolute;
            top: 16px;
            left: 12px;
            font-size: 18px;
            color: #595959;
            -webkit-transition: all 0.4s ease;
            -o-transition: all 0.4s ease;
            transition: all 0.4s ease;
        }

        .accordion li i.fa-chevron-down {
            right: 12px;
            left: auto;
            font-size: 16px;
        }

        .accordion li.open .link {
            color: #b63b4d;
        }

        .accordion li.open i {
            color: #b63b4d;
        }
        .accordion li.open i.fa-chevron-down {
            -webkit-transform: rotate(180deg);
            -ms-transform: rotate(180deg);
            -o-transform: rotate(180deg);
            transform: rotate(180deg);
        }

        /**
         * Submenu
         -----------------------------*/
        .submenu {
            display: none;
            background: #444359;
            font-size: 14px;
        }

        .submenu li {
            border-bottom: 1px solid #4b4a5e;
        }

        .submenu a {
            display: block;
            text-decoration: none;
            color: #d9d9d9;
            padding: 12px;
            padding-left: 42px;
            -webkit-transition: all 0.25s ease;
            -o-transition: all 0.25s ease;
            transition: all 0.25s ease;
        }

        .submenu a:hover {
            background: #b63b4d;
            color: #FFF;
        }


    </style>
</head>
<body>

<ul id="accordion" class="accordion">
    <li>
        <div class="link">一年级</div>
        <ul class="submenu">
            <li>Photoshop</li>
            <li>Photoshop</li>
            <li>Photoshop</li>
            <li>Photoshop</li>
            <li>Photoshop</li>
        </ul>
    </li>
    <li>
        <div class="link">二年级</div>
        <ul class="submenu">
            <li>Photoshop</li>
            <li>Photoshop</li>
            <li>Photoshop</li>
            <li>Photoshop</li>
            <li>Photoshop</li>
        </ul>
    </li>
    <li>
        <div class="link">三年级</div>
        <ul class="submenu">
            <li>Photoshop</li>
            <li>Photoshop</li>
            <li>Photoshop</li>
            <li>Photoshop</li>
            <li>Photoshop</li>
        </ul>
    </li>
</ul>
<script>
    // Dropdown Menu
    var dropdown = document.querySelectorAll('.dropdown');
    var dropdownArray = Array.prototype.slice.call(dropdown,0);
    dropdownArray.forEach(function(el){
        var button = el.querySelector('a[data-toggle="dropdown"]'),
                menu = el.querySelector('.dropdown-menu'),
                arrow = button.querySelector('i.icon-arrow');

        button.onclick = function(event) {
            if(!menu.hasClass('show')) {
                menu.classList.add('show');
                menu.classList.remove('hide');
                arrow.classList.add('open');
                arrow.classList.remove('close');
                event.preventDefault();
            }
            else {
                menu.classList.remove('show');
                menu.classList.add('hide');
                arrow.classList.remove('open');
                arrow.classList.add('close');
                event.preventDefault();
            }
        };
    });

    Element.prototype.hasClass = function(className) {
        return this.className && new RegExp("(^|\\s)" + className + "(\\s|$)").test(this.className);
    };
</script>

</body>
</html>